The sorting of mail is a very complex, time consuming task. In general, the sorting of mail is processed through many stages, including back end processes, which sort or sequence the mail in delivery order sequence. These processes can either be manual or automated, depending on the mail sorting facility, the type of mail to be sorted such as packages, flats, letters and the like. A host of other factors may also contribute to the automation of the mail sorting, from budgetary concerns to modernization initiatives to access to appropriate technologies to a host of other factors.
Most postal facilities within the United States have taken major steps toward automation by the implementation of a number of technologies. These technologies include, amongst others, letter sorters, parcel sorters, advanced tray conveyors, flat sorters and the like. As a result of these developments, postal facilities have become quite automated over the years, considerably reducing overhead costs and increasing mail throughput. However, certain processes are still manually performed such as, for example, the stacking and storage of mail trays for in subsequent operations.
By way of example, in front end processes, sorting and sequencing systems are capable of sequencing mail pieces and other product based on a two pass algorithm system. In one such known system, sorting devices include one or more feeders with feed rate capacities ranging from approximately 40,000 letters per hour and approximately 10,000 flats per hour. As the mail pieces are inducted into the system, they are first manually unloaded from trays. The trays are then placed onto a conveyor system which, in turn, transports the trays to a back end bin location or destination. Typically, two trays can be placed in each bin location.
During this processing, the mail may be processed by passing a camera, optical reading device, bar code scanner or other type of reading device used to read destination information from the mail pieces. This information is then provided to a control, which uses such information to coordinate the movements of the mail pieces to the predetermined bin locations, via diverters or other known systems. In a two pass system, the mail pieces are placed first in the sort order during this operational stage.
However, to complicate matters, there is typically more trays then available bin locations. So, in these instances, the trays become log jammed on the conveyor which, in instances, may affect the processing of the mail pieces. In these cases, an operator manually removes the trays from the conveyors, prior to entering the bin locations. The trays are then stacked on a pallet, near the conveyor, until a tray within one of the bin locations is removed. At such time, the operator has to reintroduce one of the trays from the pallet onto the conveyor for transport to the now empty bin location.
During this process, many trays become stacked on the pallet, since the amount of empty trays on the conveyor far outpaces the capacity of the sorting or sequencing machine. The stacks become unmanageable and take an inordinate amount of flooring space within the sorting facility. This in turn leads to increased costs due to, for example, the need for expensive flooring space, operator time or reduced machine throughput and lost efficiency.
The invention is directed to overcoming one or more of the problems as set forth above.